This invention relates to a hub cap for use on oil-lubricated wheel and axle assemblies of vehicles. Wheel and axle assemblies used on large trailers and truck tractors involve the rotatable mounting of a wheel, by means of a wheel hub, on a fixed axle. The wheel hub, along with oil seals at the inner bearing, defines a first part of a lubricant reservoir. Oil in the lubricant reservoir lubricates the bearing which facilitate the rotation of the wheel about the axle. The hub cap used with such an oil-lubricated wheel and axle assembly comprises a second integral part of the lubricant reservoir.
Conventional hub caps known for use with oil-lubricated wheel and axle assemblies are taught, for example, in the following United States patents.
Stephens U.S. Pat. No. 2,854,287 PA1 Steiner U.S. Pat. No. 3,089,738 PA1 Isenbarger U.S. Pat. No. 3,114,579 PA1 Isenbarger U.S. Pat. No. 3,316,022 PA1 Fruth U.S. Pat. No. 3,331,638 PA1 Brandt U.S. Pat. No. 3,395,950
It is known that the subject oil reservoirs have a tendency to leak. And so conventional hub caps have a transparent outer wall whereby the level of the oil on the interior of the reservoir can be visually inspected. If the oil level is found to be low, oil is added through a filler plug commonly provided. But sometimes a low oil level is not detected.
Especially on large vehicles, such as semi-tractors and trailers, the outer wheel bearing is smaller, and rides at a higher level than the inner wheel bearing. This relationship is seen in Stephens U.S. Pat. No. 2,854,287 where the bottom of his outer bearing 14 is disposed upwardly from the bottom of his inner bearing 15.
As the oil leaks, and the oil level recedes, the oil level drops below the bottom of the outer bearing in such reservoirs, and the outer bearing runs dry while the inner bearing is still effectively lubricated. Within a short time, the outer bearing fails because of lack of lubrication, whereupon the vehicle is effectively stopped, and out of service until the bearing is replaced.
Isenbarger U.S. Pat. No. 3,316,022 is typical of the most common hub caps which contain no oil when the oil level in the hub drops below the bottom of the smaller outer bearing. Fruth U.S. Pat. No. 3,331,638 teaches baffles for moving the oil. Miniature reservoirs between baffles of Fruth extend to an imaginary circle of lesser diameter than the center-line of the hub cap mounting holes. As indicated by study of Fruth's FIG. 1, when the oil level drops below the outer bearing, there is little oil in his hub cap.
It is an object of this invention to provide an improved hub cap which assists in sustaining the lubrication of especially the outer bearing at low oil levels.
It is another object of the invention to provide a hub cap having an expanded reservoir adapted to retain oil and apply the oil to the outer bearing when the oil level is low.
Yet another object of the invention is to provide a hub cap which defines a secondary oil reservoir when the oil level is below the peripheral center-line of the securing locus.
It is still another object to provide a hub cap having pumping baffles adapted to urging oil toward the outer bearing.
It is yet another object to provide a hub cap having filter means to trap and hold sediments in the oil.
It is a further object to provide a hub cap having magnet means to attract and hold magnetic particles and fragments in the oil.